Polysaccharide Based Polymers Produced by Scabby Cankered Cactus Pear (Opuntia ficus-indica L.) Infected by Neofusicoccum batangarum: Composition, Structure, and Chemico-Physical Properties

Neofusiccocum batangarum is the causal agent of scabby canker of cactus pear (Opuntia ficus-indica L.). The symptoms of this disease are characterized by crusty, perennial cankers, with a leathery, brown halo. Characteristically, a viscous polysaccharide exudate, caking on contact with air, leaks from cankers and forms strips or cerebriform masses on the surface of cactus pear cladodes. When this polysaccharide mass was partial purified, surprisingly, generated a gel. The TLC analysis and the HPLC profile of methyl 2-(polyhydroxyalkyl)-3-(o-tolylthiocarbomoyl)-thiazolidine-4R-carboxylates obtained from the mixture of monosaccharides produced by acid hydrolysis of the three EPSs examined in this research work [the polysaccharide component of the exudate (EPSC) and the EPSs extracted from asymptomatic (EPSH) and symptomatic (EPSD) cladodes] showed the presence of d-galactose, l-rhamnose, and d-glucose in a 1:1:0.5 ratio in EPSC while d-galactose, l-rhamnose, d-glucose, and d-xylose at the same ratio were observed in EPSH and EPSD. The presence of uronic acid residues in EPSC was also showed by solid state NMR and IR investigation. Furthermore, this manuscript reports the chemical-physical characterization of the gel produced by the infected cactus pear.

An oxidative metabolic pathway of 4-deoxy-L-erythro-5-hexoseulose uronic acid (DEHU) from alginate in an alginate-assimilating bacterium

Alginate-assimilating bacteria degrade alginate into an unsaturated monosaccharide, which is converted into 4-deoxy-L-erythro-5-hexoseulose uronic acid (DEHU). DEHU is reduced to 2-keto-3-deoxy-D-gluconate by a DEHU-specific reductase using NAD(P)H. This is followed by pyruvate production via the Entner-Doudoroff pathway. Previously, we identified FlRed as a DEHU reductase in an alginate-assimilating bacterium, Flavobacterium sp. strain UMI-01. Here, we showed that FlRed can also catalyze the oxidation of DEHU with NAD+, producing 2-keto-3-deoxy-D-glucarate (KDGR). FlRed showed a predilection for NADH and NAD+ over NADPH and NADP+, respectively, and the Km value for NADH was approximately 2.6-fold less than that for NAD+. Furthermore, we identified two key enzymes, FlDet and FlDeg, for KDGR catabolism. FlDet was identified as an enzyme of the ribonuclease activity regulator A family, which converts KDGR to α-ketoglutaric semialdehyde (α-KGSA). FlDeg, a type II α-KGSA dehydrogenase, generated α-ketoglutaric acid by oxidizing the aldehyde group of α-KGSA using NAD(P)+. Consequently, unlike the conventional DEHU reduction pathway, DEHU can be directly converted to α-ketoglutaric acid without consuming NAD(P)H. Alginate upregulated the expression of not only FlRed and two enzymes of the DEHU-reduction pathway, but also FlDet and FlDeg. These results revealed dual pathways of DEHU metabolism involving reduction or oxidation by FlRed.

Experimental Evaluation of an Antimicrobial Protein from Bacillus Amyloliquefaciens MBL27 for Wound Healing Potential in Rats

Objective: This study was aimed at assessing the ability of the antimicrobial protein (AMP) produced by Bacillus amyloliquefaciens MBL27 as a potent wound healant. Methods: Rat models were used to study the efficacy of AMP and AMP incorporated chitosan sheet along with control groups.Results: AMP and AMP incorporated chitosan sheet significantly improved wound contraction when compared to controls. Rate of wound contraction (97.23%), decreased period of epithelialization (14 days) and the levels of biochemical markers such as hydroxyproline (collagen), hexosamine, uronic acid and total protein in the granulation tissue on various days of wound healing revealed the wound healing efficacy of the AMP. The histological examinations also correlated well with the biochemical findings, confirming the wound healing efficacy of the AMP. Conclusion: The results indicate the beneficial effects of AMP from B.amyloliquefaciens MBL27 and its potential to be developed into new therapeutic agent for dermal wound healing.

Valorization of Polysaccharides Obtained from Dark Tea: Preparation, Physicochemical, Antioxidant, and Hypoglycemic Properties

The structure and hypoglycemic activity of tea polysaccharides has been extensively studied, while there are few reports on the characterization and hypoglycemic activity of dark tea polysaccharides. The crude dark tea polysaccharide (CDTPS) was optimally extracted from Fuzhuan dark tea. Six polysaccharide fractions (namely DTPS-1, DTPS-2, DTPS-3, DTPS-4, DTPS-5, and DTPS-6) were isolated from CDTPS, and their physicochemical, structural, and biological properties were compared and analyzed. The results revealed that the compositions, structural characteristics, and biological properties of the six DTPSs were different. Therein, DTPS-4 and DTPS-6 had looser morphology, faster solubility, and a more stable structure. Additionally, DTPS-4 had the optimum in vitro antioxidant capabilities, and DTPS-6 had the strongest in vitro hypoglycemic capabilities. In addition, a correlation analysis revealed that the molecular weight and uronic acid content were significantly related to their antioxidant and hypoglycemic activities. Our results indicated that DTPS-4 and DTPS-6 could be further developed into functional foods or additives, respectively.

A Novel Three-Step Extraction Strategy for High-Value Products from Red Algae Porphyridium purpureum

The microalga Porphyridium accumulates high-value compounds such as phycoerythrin, polyunsaturated fatty acids, and polysaccharides, and thus, the extraction of these compounds could significantly expand the value of Porphyridium biomass. In the present study, a novel fractional extraction strategy based on the characteristics of these compounds was established using cold water, 95% ethanol, and hot water. The yield of phycoerythrin, lipids, and polysaccharides was 63.3, 74.3, and 75.2%, respectively. The phycoerythrin exhibited excellent fluorescence characteristics but had low purity. The crude lipid was dark with poor fluidity. Digalactosyldiacylglycerol and sulphoquinovosyldiacylglycerol containing C20:5 and C20:4 were the most abundant glycerolipids, while glucose, xylose, and galactose constituted the intracellular polysaccharides that had covalently bound to proteins (8.01%), uronic acid (4.13%), and sulfate (8.31%). Compared with polysaccharides and crude lipids, crude phycoerythrin showed the best antioxidant activity. Overall, the three-step fractional extraction process was feasible for Porphyridium; however, further purification is necessary for downstream applications.

Ancient origin of fucosylated xyloglucan in charophycean green algae

The charophycean green algae (CGA or basal streptophytes) are of particular evolutionary significance because their ancestors gave rise to land plants. One outstanding feature of these algae is that their cell walls exhibit remarkable similarities to those of land plants. Xyloglucan (XyG) is a major structural component of the cell walls of most land plants and was originally thought to be absent in CGA. This study presents evidence that XyG evolved in the CGA. This is based on a) the identification of orthologs of the genetic machinery to produce XyG, b) the identification of XyG in a range of CGA and, c) the structural elucidation of XyG, including uronic acid-containing XyG, in selected CGA. Most notably, XyG fucosylation, a feature considered as a late evolutionary elaboration of the basic XyG structure and orthologs to the corresponding biosynthetic enzymes are shown to be present in Mesotaenium caldariorum.

Ekstraksi Polisakarida Sulfat dari Sargassum polycystum dengan Metode Microwave Assisted Extraction dan Uji Toksisitasnya

Sargassum polycystum merupakan alga cokelat penghasil polisakarida sulfat yang memiliki aktivitas farmakologi yang menjanjikan. Selama ini metode ekstraksi polisakarida sulfat masih bersifat konvensional (seperti maserasi, sokletasi, dan refluks) yang memerlukan waktu ekstraksi relatif lama (4-6 jam). Penelitian ini bertujuan untuk mengekstraksi polisakarida sulfat menggunakan metode Microwave Assisted Extraction (MAE) serta melakukan uji toksisitasnya. Karakterisasi ekstrak polisakarida sulfat menggunakan spektrofotometer UV-Visible dan Fourier Transform Infrared (FT- IR). Uji toksisitas terhadap larva Artemia salina Leach dilakukan dengan metode Brine Shrimp Lethality Test (BSLT). Hasil ekstraksi polisakarida sulfat diperoleh rendemen sebesar 3,42±0,01% dimana tidak jauh berbeda dari metode konvensional. Hasil perhitungan bobot susut pengeringan polisakarida sulfat 7,60±0,085%. Karakterisasi polisakarida sulfat dengan spektrofotometer UV- Visible diperoleh panjang gelombang optimum pada 270 nm. Hasil spektrum FT-IR terdapat gugus fukosa yang dihubungkan oleh gugus sulfat dan O-Sulfat yang mengindikasikan adanya fukoidan. Selain itu masih ditemukan peregangan ester C=O yang menunjukan adanya asam uronat. Asam tersebut merupakan penyusun alginat dimana bukan merupakan polisakarida sulfat. Dari uji toksisitas diperoleh nilai LC50 polisakarida sulfat terhadap larva A. salina Leach sebesar 113,11 mg/mL yang tergolong kategori toksik. Ekstraksi polisakarida sulfat menggunakan MAE dapat mempercepat waktu ekstraksi dibandingkan dengan metode konvensional, tetapi perlu dilakukan tahap selanjutnya untuk menghilangkan senyawa pengotor lainnya seperti asam uronat. ABSTRACTSargassum polycystum, a brown algae, produces sulfate polysaccharides that have promising pharmacological activity. To date, the extraction of sulfate polysaccharide is still conventional (such as maceration, shoxletation and reflux) and requires a relatively long time (4-6 h). This study aims to extract the sulfate polysaccharides using the Microwave Assisted Extraction (MAE) and assess the toxycity. Sulfate polysaccharide extract was characterized by UV-Visible and Fourier Transform Infrared (FT-IR) spectrophotometer and tested for its toxicity against Artemia salina Leach larvae using the Brine Shrimp Lethality Test (BSLT) method. The yield of sulfate polysaccharide extraction was 3.42±0.01% which is not much different from conventional methods, but the advantage of the MAE method is in terms of time efficiency. The result of the calculation of the drying shrinkage weight of the sulfate polysaccharide is 7.60±0.085%. Characterization of sulfate polysaccharide using a UV-Visible spectrophotometer obtained an optimum wavelength at 270 nm. Based on spectra of FT-IR, it was identified that there are fucose groups which are connected by sulfate and O-Sulfate groups which indicates the presence of fucoidan. In addition, there was still a stretch of ester C=O which indicates the presence of uronic acid. The acid is a constituent of alginate which is not a sulfate polysaccharide. The LC50 value of sulfate polysaccharide against A. salina Leach larvae was 113.11 mg/mL which was classified as toxic. The extraction of sulfate polysaccharides using MAE can speed up the extraction time compared to conventional method, but a further step is needed to remove other impurities such as uronic acid

Thermal degradation of hemicellulose and cellulose in ball-milled cedar and beech wood

The thermal degradation reactivities of hemicellulose and cellulose in wood cell walls are significantly different from the thermal degradation behavior of the respective isolated components. Furthermore, the degradation of Japanese cedar (Cryptomeria japonica, a softwood) is distinct from that of Japanese beech (Fagus crenata, a hardwood). Lignin and uronic acid are believed to play crucial roles in governing this behavior. In this study, the effects of ball milling for various durations of time on the degradation reactivities of cedar and beech woods were evaluated based on the recovery rates of hydrolyzable sugars from pyrolyzed wood samples. The applied ball-milling treatment cleaved the lignin β-ether bonds and reduced the crystallinity of cellulose, as determined by X-ray diffraction. Both xylan and glucomannan degraded in a similar temperature range, although the isolated components exhibited different reactivities because of the catalytic effect of uronic acid bound to the xylose chains. These observations can be explained by the more homogeneous distribution of uronic acid in the matrix of cell walls as a result of ball milling. As observed for holocelluloses, cellulose in the ball-milled woods degraded in two temperature ranges (below 320 °C and above); a significant amount of cellulose degraded in the lower temperature range, which significantly changed the shapes of the thermogravimetric curves. This report compares the results obtained for cedar and beech woods, and discusses them in terms of the thermal degradation of the matrix and cellulose microfibrils in wood cell walls and role of lignin. Such information is crucial for understanding the pyrolysis and heat treatment of wood.

Chemical synthesis of C6-tetrazole D-mannose building blocks and access to a bioisostere of mannuronic acid 1-phosphate

Alginate, an anionic polysaccharide, is an important industrial biomaterial naturally harvested from seaweed. Many of its important physicochemical properties derive from the presence of charged carboxylate groups, presented as uronic acids, within the polysaccharide backbone. An ability to design and synthesise isosteres of these carboxylates would ultimately enable access to new alginate systems possessing different physicochemical properties. We present herein an approach to the chemical synthesis of alginate building blocks, modified at the carboxylate C6 position with bioisosteric tetrazole. The development of this synthesis enables utilisation of C6-tetrazole donors to deliver anomeric phosphate and 3-aminopropyl free sugars containing this motif. Access to these building blocks will further enable glycosylation methodologies to be explored that incorporate tetrazole as a bioisostere within uronic acid-containing carbohydrates.